In a conventional broadband wireless access system, an MS may request an uplink bandwidth by transmitting a Bandwidth Request (BR) to a BS in a Medium Access Control (MAC) signaling header or a MAC subheader. The uplink BR is made per connection between the MS and the BS.
A conventional BR header has the format illustrated in FIG. 1. The MS may request an uplink bandwidth of up to 512 KB using this BR header.
Table 1 below lists fields of the conventional BR header illustrated in FIG. 1.
TABLE 1LengthName(bit)DescriptionBR19Bandwidth request. The number of bytes of UL bandwidthrequested by the Subscriber Station (SS). The BR is forthe CID. The request shall not include any PHY overhead.CID16Connection identifier.EC1Always set to zeroHCS8Header check sequence.HT1Header type = 1.Type3Indicates the type of BRIGHTNESS header.
A MAC signaling header that carries a BR along with an Uplink Transmit (UL Tx) power report is formatted as illustrated in FIG. 2.
Table 2 describes fields of the MAC signaling header illustrated in FIG. 2. The MS may request an uplink bandwidth of up to 2 KB by this MAC signaling header.
TABLE 2LengthName(bit)DescriptionType3The type of BR and UL Tx power report header.BR11Bandwidth request. The number of bytes of UL bandwidth requested by the MS. The BR is forthe CID. The request shall not include any PHY overhead. It is incremental BR. In case of the Extended rtPS, the BS changes its polling size into the value specified in this field.UL Tx 8UL Tx power level in dBm for the burst that carries powerthis header. The value shall be estimated and reported for the burst.CID16The connection identifier that shall indicate the connection for which UL bandwidth is requested.HCS8Header check sequence.
Besides the above two headers, a Bandwidth Request/Carrier to Interference and Noise Ratio (BR/CINR) report header and a BR with UL sleep control header are available for requesting an uplink bandwidth. The MS may request an uplink bandwidth of up to 2 KB by the BR/CINR report header or the BR with UL sleep control header.
Because the MS requests an uplink bandwidth on a connection basis in the conventional broadband wireless access system, the BR always includes a 16-bit Connection Identifier (CID). Bits required to express the maximum requested bandwidth size 512 KB or 2 KB are simply included in each BR header. Therefore, the conventional bandwidth request method may not prevent the increase of unnecessary overhead.